Initial network entry to a communications system

ABSTRACT

In an embodiment, a user terminal includes a connection manager component configured to generate an initial network entry request; an antenna assembly communicatively coupled to the connection manager and configured, in response to the initial network entry request, to find a satellite based on a search of a sky, wherein the satellite comprises a satellite assigned to downlink to a geographic cell associated with the user terminal; and a media access control (MAC) layer component communicatively coupled to the connection manager, the MAC layer component configured to generate an uplink radio frame including a random access channel (RACH) request associated with the initial network entry request at a particular portion of the uplink radio frame for the satellite, wherein the particular portion is selected by the MAC layer component from among a plurality of portions of the uplink radio frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/032,868, filed on Jun. 1, 2020, entitled “INITIAL NETWORK ENTRYTO A COMMUNICATION SYSTEM”, the contents of which are herebyincorporated by reference in their entirety and for all purposes.

TECHNICAL FIELD

The present disclosure generally relates to wireless communicationssystems and, more specifically, to performing an initial network entryto a communication system.

BACKGROUND

In wireless communications systems, information is relayed from anoriginating device to a destination device via one or moreintermediating devices, thereby forming a communication chain. Thecommunication link between one or more respective pairs of devices inthe communication chain can comprise wireless communication links. Ifthe information comprises a request, data for which receipt is to beacknowledged, a command for which receipt is to be acknowledged, and/orthe like, appropriate information is relayed in reverse back to theoriginating device. Typically many such one-way or round-tripcommunications occur for the originating device.

In order for ground equipment to communicate information within thecommunications system under normal operating conditions, such groundequipment first registers with the communications system. In satellitecommunications systems, the registration process for the groundequipment occurs via a satellite. Registering confers requisite checksfor both the ground equipment and satellite, and provides the groundequipment with various resource allocation information for the groundequipment to properly transmit and receive communications withoutconflicting with other communications within the communications system(e.g., communications between other ground equipment and the samesatellite).

Ground equipment has limited or no information about the rest of thecommunications system, especially at start up, since network informationsuch as satellite locations or orbiting schedule is provided bysatellites to which they are able to establish and maintain acommunication link.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of theembodiments of the present disclosure will become more readilyappreciated as the same become better understood by reference to thefollowing detailed description, when taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 illustrates a diagram showing an example wireless communicationssystem in accordance with various aspects of the present disclosure.

FIG. 2 illustrates a block diagram showing a subset of nodes included inthe system of FIG. 1 in accordance with various aspects of the presentdisclosure.

FIG. 3A illustrates a block diagram showing example components includedin the user terminal or equipment associated with initial network entryin accordance with various aspects of the present disclosure.

FIG. 3B illustrates a block diagram showing example components includedin the satellite associated with initial network entry in accordancewith various aspects of the present disclosure.

FIGS. 4A-4C illustrate a flow diagram showing a process for performinginitial network entry for a user terminal in accordance with variousaspects of the present disclosure.

FIG. 5 illustrates a timing diagram relating to the process of FIGS.4A-4C in accordance with various aspects of the present disclosure.

FIG. 6 illustrates an example uplink (UL) radio frame including aplurality of random access channel (RACH) resources in accordance withvarious aspects of the present disclosure.

FIG. 7 illustrates an example process for detection of RACH requests inaccordance with various aspects of the present disclosure.

FIG. 8 illustrates a block diagram showing an example platform or devicethat can be implemented in the user terminal and/or satellite inaccordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

As previously explained, in order for ground equipment to communicateinformation within a wireless communications system under normaloperating conditions, such ground equipment registers with thecommunications system. Registering confers requisite checks for both theground equipment and satellite and can provide the ground equipment withvarious resource allocation information for the ground equipment totransmit and receive communications without conflicting with othercommunications within the communications system (e.g., communicationsbetween other ground equipment and the same satellite).

Ground equipment has limited or no information about the rest of thecommunications system, especially at start up, since network informationsuch as satellite locations or orbiting schedule is provided bysatellites to which they are able to establish and maintain acommunication link. It would be advantageous for ground equipmentassociated with a user having little or no information about the networkto be able to initiate registration or network entry. It would also beadvantageous for ground equipment associated with a user to be able toproperly enter a network of the communications system without havingprior knowledge of satellite positions in a relative short time period.In some aspects, systems and techniques of the present disclosure aredirected to these and other improvements in network entry tocommunications systems or portions thereof.

In at least some examples, systems, and methods are disclosed relatingto initial network entry techniques to a communications system. Theseand other aspects of the present disclosure will be more fully describedbelow.

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific embodiments thereof havebeen shown by way of example in the drawings and will be describedherein in detail. It should be understood, however, that there is nointent to limit the concepts of the present disclosure to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives consistent with the presentdisclosure and the appended claims.

References in the specification to “one embodiment,” “an embodiment,”“an illustrative embodiment,” etc., indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but every embodiment may or may not necessarily includethat particular feature, structure, or characteristic. Moreover, suchphrases are not necessarily referring to the same embodiment. Further,when a particular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art to affect such feature, structure,or characteristic in connection with other embodiments whether or notexplicitly described. Additionally, it should be appreciated that itemsincluded in a list in the form of “at least one A, B, and C” can mean(A); (B); (C); (A and B); (B and C); (A and C); or (A, B, and C).Similarly, items listed in the form of “at least one of A, B, or C” canmean (A); (B); (C); (A and B); (B and C); (A and C); or (A, B, and C).

Language such as “top surface”, “bottom surface”, “vertical”,“horizontal”, and “lateral” in the present disclosure is meant toprovide orientation for the reader with reference to the drawings and isnot intended to be the required orientation of the components or toimpart orientation limitations into the claims.

In the drawings, some structural or method features may be shown inspecific arrangements and/or orderings. However, it should beappreciated that such specific arrangements and/or orderings may not berequired. Rather, in some embodiments, such features may be arranged ina different manner and/or order than shown in the illustrative figures.Additionally, the inclusion of a structural or method feature in aparticular figure is not meant to imply that such feature is required inall embodiments and, in some embodiments, it may not be included or maybe combined with other features.

Many embodiments of the technology described herein may take the form ofcomputer- or processor-executable instructions, including routinesexecuted by a programmable computer, processor, controller, chip, and/orthe like. Those skilled in the relevant art will appreciate that thetechnology can be practiced on computer/controller systems other thanthose shown and described above. The technology can be embodied in aspecial-purpose computer, controller, or processor that is specificallyprogrammed, configured or constructed to perform one or more of thecomputer-executable instructions described above. Accordingly, the terms“computer,” “controller,” “processor,” or the like as generally usedherein refer to any data processor and can include Internet appliancesand hand-held devices (including palm-top computers, wearable computers,cellular or mobile phones, multi-processor systems, processor-based orprogrammable consumer electronics, network computers, mini computers,and the like). Information handled by these computers can be presentedat any suitable display medium, including an organic light emittingdiode (OLED) display or liquid crystal display (LCD).

FIG. 1 illustrates a diagram showing an example wireless communicationssystem 100 in accordance with various aspects of the present disclosure.System 100 comprises a satellite-based communications system including aplurality of satellites orbiting Earth in, for example, anon-geostationary orbit (NGO or NGSO) constellation. It is understoodthat system 100 can also comprise any of a variety of wirelesscommunications systems such as, but not limited to, a low earth orbiting(LEO) communications system, a non-earth based communications system, aground-based communications system, a space-based communications system,and/or the like.

Of the plurality of satellites comprising the satellite constellation,at least three satellites of the plurality of satellites (e.g.,satellites 102, 104, and 106) are shown in FIG. 1 for illustrativepurposes. System 100 further includes ground or terrestrial basedequipment configured to communicate with the plurality of satellites,such equipment including a plurality of user equipment and a pluralityof gateways. User equipment 110, 112, 114, and 116 of the plurality ofuser equipment are shown in FIG. 1 . Gateways 120, 122 of the pluralityof gateways are also shown in FIG. 1 . Each of the satellites, userequipment, and gateways within system 100 is also referred to as a node,system node, communication node, and/or the like.

Each user equipment of the plurality of user equipment is associatedwith a particular user. User equipment is configured to serve as aconduit between the particular user's device(s) and a satellite of theplurality of satellites which is in communication range of the userequipment, such that the particular user's device(s) can have access toInternet 126 via a network 124. Each user equipment is particularlypositioned in proximity to the associated user's device(s). For example,user equipment 110, 112, and 116 are located on the respective users'building roof and user equipment 114 is located on a yard of the user'sbuilding. A variety of other locations are also contemplated for theuser equipment. User equipment may also be referred to as userterminals, end use terminals, end terminals, user ground equipment,ground-based communication device, and/or the like.

At any given time, a communication link established between a particularsatellite and a particular user equipment facilitates access to Internet126 by the user associated with the particular user equipment. One ormore user devices (e.g., a smartphone, a tablet, a laptop, an Internetof Things (IoT) device, wearable device, and/or the like) is in wired or(short range) wireless communication with user equipment 110. If, forexample, the user requests a web page via a user device 111, the userdevice relays the request to user equipment 110. User equipment 110 canestablish a communication link 130 to the satellite 102 and transmit therequest. Satellite 102, in response, establishes a communication link132 with an accessible gateway 120 to relay the request. The gateway 120has wired connections to the network 124. Network 124 has wiredconnections to Internet 126. The request is relayed from gateway 120 tonetwork 124 to Internet 126. The data associated with rendering therequested web page is returned in the reverse path, from the network124, gateway 120, communication link 132, satellite 102, communicationlink 130, user equipment 110, and to the originating user device 111.The requested web page is then rendered on the originating user device111.

If satellite 102 moves out of position relative to user equipment 110before the requested data can be provided to user equipment 110 (orotherwise becomes unavailable), then gateway 120 establishes acommunication pathway 134, 136 with a different satellite, such assatellite 104, to provide the requested data.

In some embodiments, network 124 comprises a private network and theInternet 126 comprises a public network. Network 124 can comprise apoint of presence (PoP). Network 124 can include servers, routers,network switches, multiplexers, central control systems, and/or othernetwork interface equipment. One or more of network 124 can be includedin system 100. For instance, the number of network 124 can be equal toor less than the number of gateways of the plurality of gateways.

In some embodiments, one or more gateway of the plurality of gatewayscomprises repeaters that lack a wired connection to the network 124. Arepeater is configured to relay communications to and/or from asatellite that is a different satellite from the one that directlycommunicated with a user equipment or gateway. A repeater is configuredto be part of the communication pathway between a user equipment andgateway. A repeater may be accessed in cases where a satellite does nothave access to a gateway, and thus has to send its communication toanother satellite that has access to a gateway via the repeater.Repeaters can be located terrestrially, on water (e.g., on ships orbuoys), in airspace below satellite altitudes (e.g., on an airplane orballoon), and/or other Earth-based locations. Alternatively, repeatersmay be optional if the “repeater,” relaying, and/or bufferingfunctionalities are handled by network 124. Accordingly, the pluralityof gateways may also be referred to as Earth-based network nodes,Earth-based communication nodes, and/or the like.

In some embodiments, one or more transmitter system and one or morereceiver system are included in each user equipment, satellite, andgateway (and repeater) of system 100. A transmitter system can include,without limitation, components to generate and transmit radio frequency(RF) signals based on data signals provided by a modem (e.g.,beamforming components, signal encoding components, baseband section,modulation section, antenna, and associated circuitry). A receiversystem can include, without limitation, components to receive RF signalsand recover data signals from the received RF signals to provide to amodem (e.g., signal decoding components, baseband section, modulationsection, antenna, and associated circuitry). If a node includes morethan one transmitter system, the respective transmitter systems may bethe same or different from each other. More than one receiver systemincluded in a node may similarly be the same or different from eachother.

Wireless communication using NGO satellite constellations poses certainchallenges for ground-based user equipment. In contrast togeosynchronous satellites, in which each satellite appears at a fixedpoint in the sky, NGO satellite constellations are composed ofsatellites that rapidly move across the sky in different directionsrelative to the ground. The user equipment finds and tracks thesesatellites to establish and maintain wireless communication with them.

FIG. 2 illustrates a block diagram showing a subset of nodes included inthe system 100 in accordance with various aspects of the presentdisclosure. As shown, a bi-directional communication link is to beestablished and maintained between each pair of nodes (e.g., betweenuser device 111 and user equipment 110, between user equipment 110 andsatellite 102, etc.), as will be described in detail below. Acommunication link 202 transports user and control plane trafficinformation between gateway 120 and network 124. A communication link204 transports user traffic between network 124 and Internet 126. Userequipment 110 is also referred to as a user terminal or UT. Satellite102 is also referred to as a SAT. Gateway 120 is also referred to as aGW.

FIG. 3A illustrates a block diagram showing example components includedin the user terminal or equipment 110 associated with initial networkentry in accordance with various aspects of the present disclosure. Insome embodiments, user terminal 110 includes, without limitation, a userterminal (UT) global positioning system (GPS) 302, a UT connectionmanager (CM) 304, a UT layer 3 (L3) 306, a UT upper media access control(UMAC) 308, a UT lower media access control (LMAC) 310, a UT layer 1(L1) 314, and a UT beam pointing service (BPS) 316.

UT GPS 302 includes a GPS receiver (e.g., an integrated circuit (IC)chip) that is configured to detect the geographic location of the userterminal 110. UT GPS 302 comprises at least a portion of an inertialmeasurement unit (IMU) included in the user terminal 110, in someembodiments. Or UT GPS 302 can comprise a separate component from anIMU. UT GPS 302 can comprise other types of position determining systemcomponent than GPS. UT CM 304 is configured to manage establishing aconnection to the network 124 and the associated information exchangewith satellite 102 for initial network entry, as will be described indetail below. Initial network entry may be initiated if user terminal110 is starting up for the first time, rebooted, moved to a differentlocation after initial network entry was previously completed, loses aconnection to the network for whatever reason, and/or the like.

UT L3 306, UT UMAC 308, UT LMAC 310, and UT L1 314 comprise differentabstraction layers (or sublayers) of an Open Systems Interconnection(OSI) model, which is a conceptual model or construct to characterizethe communication functions or protocols implemented in the system 100independent of its underlying structures and technology. A given layerserves the layer above it and is served by the layer below it. A givenlayer receives data from the layer below and provides data to the layerabove. The degree of abstraction increases the higher the layer withinthe OSI model.

UT L1 314 comprises the lowest layer of the OSI model. UT L1 314 is alsoreferred to as a physical layer (PHY layer) and is associated withorthogonal code based signals or waveforms used for communicationswithin the system 100. The orthogonal code based signals or waveformshave a particular signal or waveform structure such as a particularradio frame structure and the substructures within the radio frame. Datacommunicated between nodes of system 100 (e.g., payload data, downlinktiming allocations, uplink timing allocations, scheduling information,resource block allocations, satellite ephemeris, commands,acknowledgements, requests, etc.) are carried in particular portions ofeach radio frame in the time and frequency domains. As an example, theorthogonal code based signals or waveforms can comprise orthogonalfrequency division multiplexing (OFDM) signals or waveforms.

UT UMAC 308 and UT LMAC 310 comprise sublayers of a UT layer 2 (L2) 312.UT L2 312 is the layer immediately above UT L1 314. UT L2 312 isconfigured to abstract data from UT L1 314 and perform dataencapsulation functions to form data packets suitable for UT L3 306. Insome embodiments, UT L2 312 is configured to: (a) encapsulate datapackets from UT L3 306 and add L2 headers suitable for UT L1 314, at thetransmitter side, (b) remove L2 headers and decapulsate packets from UTL1 314 suitable for UT L3 306, at the receiver side, and (c) generate(Tx) and/or incorporate (Rx) control signaling messages (e.g., RACH,UL-map, etc.). UT L2 312 is also referred to as a MAC layer.

UT L3 306 comprises a layer immediately above UT L2 312. UT UMAC 308 isdisposed closer to UT L3 306 than UT LMAC 310. UT L3 306 is alsoreferred to as a network layer or a higher layer of the OSI model. UT L3306 is configured to facilitate: (a) generation and transport of datapackets from UT L2 312 to other nodes, devices, or networks, such aswith satellite 102, and (b) routing of data packets received from othernodes, devices, or networks to lower layers of the OSI model accordingto intended destinations.

UT BPS 316 comprises circuitry, antenna(s), electrical components,processors, algorithms, and/or other components associated withgeneration and transmission of transmit beams, receiving and processingof receive beams, and the digital interface connecting to UT L1 314. UTBPS 316 includes, without limitation, beamforming components, beamsteering controller components, transmitter components, receivercomponents, antennas, and/or the like.

FIG. 3B illustrates a block diagram showing example components includedin the satellite 102 associated with initial network entry in accordancewith various aspects of the present disclosure. In some embodiments,satellite 102 includes, without limitation, a satellite (SAT) CM 324, aSAT L3 326, a SAT UMAC 328, a SAT LMAC 330, a SAT L1 334, and a SAT BPS336. SAT UMAC 328 and SAT LMAC 330 comprise sublayers of a SAT layer 2(L2) 332. SAT CM 324, SAT L3 326, SAT UMAC 328, SAT LMAC 330, SAT L2332, SAT L1 334, and SAT BPS 336 are capable of performing operationssimilar to respective UT CM 304, UT L3 306, UT UMAC 308, UT LMAC 310, UTL2 312, UT L1 314, and UT BPS 316. Moreover, one or more of SAT CM 324,SAT L3 326, SAT UMAC 328, SAT LMAC 330, SAT L2 332, SAT L1 334, or SATBPS 336 is capable of performing or performs additional operationsrelative to user terminal 110 because of the satellite's additionalresponsibilities to communicate with more than one user terminalsimultaneously, having more than one beam, is a full duplex mode node(while user terminal 110 can be a half duplex mode node), communicatewith gateway 120, and/or the like.

In some embodiments, one or more of components 302-316 and 324-336 (or aportion thereof) comprises one or more instructions embodied within atangible or non-transitory machine (e.g., computer) readable storagemedium, which when executed by a machine causes the machine to performthe operations described herein. One or more processor can be includedin each of user terminal 110 or satellite 102 (not shown) to execute oneor more of components 302-316 and 324-336 (or a portion thereof).Components 302-316 and 324-336 (or a portion thereof) can be referred toas modules, engines, software, routines, code, applications, programs,and/or the like. In alternative embodiments, one or more of components302-316 and 324-336 (or a portion thereof) can be implemented asfirmware or hardware such as, but not limited to, an applicationspecific integrated circuit (ASIC), programmable array logic (PAL),field programmable gate array (FPGA), and/or the like. In otherembodiments, one or more of components 302-316 and 324-336 (or a portionthereof) can be implemented as software while other of the components302-316 and 324-336 (or a portion thereof) can be implemented asfirmware and/or hardware.

Each of the user terminals of system 100 initiates and completes initialnetwork entry (INE) with a satellite before normal or regularcommunications can commence for the user terminal within the system 100.A user terminal (e.g., user terminal 110) may initiate initial networkentry process if the user terminal is turned on for the first time (aspart of installation), if the user terminal is moved to a new locationafter initial network entry has been previously completed (e.g., usermoves to a new residence and relocates his or her user terminal), and/orthe like. At the start of initial network entry operations, userterminal 110 has little or no information about the system 100.

From the user terminals perspective, satellite positions are usuallyunknown prior to contact with the satellite constellation, especially ifthe satellites are the user terminals' sole source of data connectivity.Even if a given user terminal established contact with one or moresatellites in the past, previous knowledge of satellite orbits(ephemeris) quickly becomes outdated, since the exact satellitetrajectories are subject to change depending on a number of factors suchas, but not limited to, the condition and health of constituentsatellites, engine burn plans, operating requirements, and/or the like.Low-Earth orbit satellites, in particular, can be affected byunpredictable drag forces and have orbital trajectories that can bedifficult to extrapolate very far into the future.

Each satellite within the constellation can operate a plurality ofbeams, with one or more beams of the plurality of beams operating at adifferent frequency from each other. User terminals typically do notknow the particular operating frequency(ies) of the satellite beams.This means that even if a user terminal finds a satellite beam, the userterminal may not be able to decode the downlink beam received from thesatellite until the operating frequency has been determined.

The three-dimensional orientation of the antenna (e.g., a phased arrayantenna) included in the user terminal is also unknown prior to contactwith a satellite. The antenna beam—transmit beam and/or receive beam—isconfigured or electronically steered to have a particular beam pointingdirection, which is a function of the user terminal's own orientation.

Accordingly, at start of initial network entry operations, satellitepositions are unknown to the user terminal 110, satellite operatingfrequencies are unknown to user terminal 110, and the orientation ofuser terminal 110 (and in particular, of its antenna) is unknown.Nevertheless, user terminal 110 (and all of the remaining user terminalsof system 100) is capable of completing initial network entry asdisclosed herein.

FIGS. 4A-4C illustrate a flow diagram showing a process 400 forperforming initial network entry for user terminal 110 in accordancewith various aspects of the present disclosure. FIG. 5 illustrates atiming diagram 500 relating to the process 400 in accordance withvarious aspects of the present disclosure. FIGS. 4A-4C and 5 aredescribed below in conjunction with each other.

At block 402, UT GPS 302 is configured to obtain GPS information or dataassociated with user terminal 110. The obtained GPS information isprovided to UT L1 314.

At block 404, satellite discovery is performed. Satellite discovery caninclude user terminal 110 conducting a scan or search of the sky to findany satellite of the constellation assigned to downlink to thegeographic cell or sector associated with user terminal 110. In someexamples, the UT CM 304 can send a satellite discovery request to the UTUMAC 308 to initiate the satellite discovery, and the UT UMAC 308 canreturn satellite ephemeris information (e.g., satellite location,timing, etc.) to the UT CM 304. In some examples, UT BPS 316 can use thesatellite ephemeris information to conduct the scan or search. The scanor search can include sequentially changing the beam pointing direction(also referred to as the beam pointing vector) of the receive antennaincluded in the user terminal 110 in accordance with a pre-defined scanor search pattern.

At each beam pointing direction or vector, UT BPS 316 can wait longenough to receive a possible downlink signal from a satellite beforechanging to the next beam pointing direction. If no downlink signal isdetected from the scan, the scan can be repeated with UT BPS 316 set toa different satellite frequency or other parameter. If a downlink signalis detected, another scan or search may be performed around the beampointing direction at which the downlink signal was detected (thisscan/search can include a finer scan than the previous scan/search) torefine the beam pointing direction to a direction associated with thehighest (or higher) signal quality strength. At the conclusion ofsatellite discovery, a satellite has been found (e.g., satellite 102)and a particular beam pointing direction to establish and maintain acommunication link with the found satellite (at least long enough tocomplete initial network entry) is also known.

At block 406, UT CM 304 generates an initial INE request or initiates anINE request to initiate initial network entry into the system 100. TheINE request is provided to UT UMAC 308. At block 408, UT UMAC 308 canconfigure the user terminal 110 into receive mode. In some cases, the UTCM 304 can generate the initial INE request or intiate the INE requestafter the UT UMAC 308 configures the user terminal 110 into receivemode. In other cases, the UT CM 304 can generate the initial INE requestor intiate the INE request before the UT UMAC 308 configures the userterminal 110 into receive mode. For example, in some cases, the UT UMAC308 can configure the user terminal 110 into receive mode in response toreceiving the INE request. Configuring or switching to receive mode caninclude readying various hardware, firmware, and/or software componentsassociated with receiving and processing RF signals. For example,without limitation, UT UMAC 308 exchanges L2 RX Up messages orinformation with UT LMAC 310; followed by UT UMAC 308 exchanging L1 RXUp messages or information with UT L1 314; and then UT L1 314 generatingand sending BPS RX Configuration messages or information to UT BPS 316.

Satellite 102 can be configured to generate and broadcast a variety ofnetwork-related information or commands to one or more cells (or portionof the cell(s)) covered by satellite 102. As the network-relatedinformation updates over time, such updates can also be provided to thegroup of user terminals located within the one or more cells (or portionof the cell(s)) associated with satellite 102. An example of suchnetwork-related information can include uplink-mapping information(UL-map) included in a downlink radio frame. The UL-map can include, forexample and without limitation, information which indicates to each userterminal of the group of user terminals the portion(s) of the uplink(UL) radio frame allocated to that user terminal, and schedulinginformation indicating when that user terminal is to transmit an uplinkradio frame to satellite 102 so that the uplink radio frame is receivedby the satellite 102 at the proper time relative to the uplink radioframes transmitted by the other user terminals of the group of userterminals. Each user terminal (already authenticated to the network) canbe provided a dedicated grant for the uplink. For new user terminals toenter the network, the UL-map can also include an INE random accessprocedure (RACH) resource allocation in lieu of the dedicated grant. TheUL-map can include additional information relating to uplink radio frameusage by each user terminal of the group of user terminals.

While blocks 402-408 are performed, SAT LMAC 330 is configured togenerate and provide a UL-map to SAT L 1334, at block 410. The UL-map istransmitted by satellite 102 (e.g., via SAT BPS 336) over-the-air. Insome examples, user terminal 112 is unable to detect the UL-map untilthe satellite discovery at block 404. At block 410, a UL-map issequentially generated and transmitted as updates occur, on a periodicbasis, and/or other pre-defined schedule.

At block 412, a UL-map generated by SAT LMAC 330 and transmitted orbroadcast over-the-air (OTA) is received by user terminal 110. Inresponse to receipt of the UL-map, UT UMAC 308 configures the userterminal 110 into transmit mode, at block 414. Configuring or switchingto transmit mode can include readying various hardware, firmware, and/orsoftware components associated with processing data signals fortransmission. For example, without limitation, UT UMAC 308 exchanges L2TX Up messages or information with UT LMAC 310; followed by UT UMAC 308exchanging L1 TX Up messages or information with UT L1 314; and then UTL1 314 generating and sending BPS TX Configuration messages orinformation to UT BPS 316.

With the user terminal 110 in transmit mode, UT UMAC 308 is configuredto start the RACH procedure by generating a RACH request and causing UTBPS 316 to transmit the RACH request, at block 416. In some cases, theRACH request may include a short UT address (also referred to as aRACH-service identifier (R-SID)). The received UL-map providesinformation (e.g., the INE RACH resource allocation) on when and wherein an uplink radio frame to make the RACH request. The RACH request maybe received by satellite 102, at block 422. If the RACH request isproperly received by satellite 102, then satellite 102 is configured toallocate UL resources to the user terminal 110 in the UL-map for thenext radio frame after authentication of the user terminal 110 with thenetwork 124. User terminal 110 is registered in SAT L2 332 and includedin a UL-map schedule prior to authentication with network 124.

If UL resource allocation for user terminal 110 is not detected in theUL-map (no branch of block 418) in a defined period, then process 400proceeds to return to block 416 to send another RACH request. If ULresource allocation is detected (yes branch of block 418), then UT LMAC310 initiates an UT INE request to satellite 102 at block 430 and waitsfor the next UL-map.

If satellite 102 receives the RACH request from user terminal 110, atblock 422, SAT LMAC 330 can extract at least a short UT address (alsoreferred to as a RACH-service identifier (R-SID) included in the RACHrequest, at block 424. The short UT address is a temporary identifier ofthe user terminal 110 for INE purposes. In some cases, a RACH requestcan also include other information such as a unique identification blobfor the short UT address, which can be used for contention resolution.In some cases, SAT LMAC 330 can include the extracted short UT addressin the following UL-MAP scheduling.

Satellite 102 can allocate a grant for the R-SID in the next UL-map(e.g., the UL resource allocation in the UL-map). The UL-map associatedwith the short UT address (e.g., R-SID) is generated and transmitted atblock 426. Such UL-map is received by user terminal 110 and provided toUT LMAC 310, at block 428. In some embodiments, the UL-map can be aUL-map dedicated to the short UT address.

Because each user terminal sending a RACH request selects its R-SIDindependent of other user terminals that may also be sending a RACHrequest at the same time (and also independent of satellites), it ispossible for more than one user terminal to attempt to use the sameR-SID at the same time. Such situation can be a reason for the RACHrequests from those user terminals to be rejected or otherwise not begranted UL resources to continue INE. Such user terminals send anotherRACH request at a later point in time.

Upon receipt of the UL-map with the R-SID grant or resource allocation,at block 428, UT LMAC 310 decodes the grant or UL resources allocatedfor the R-SID and facilitates generation and transmission of a UT INErequest (also referred to as an INE request) in an uplink radio frame,as block 430. The detected UL resource permits establishing the L2 (MAC)control plane between the user terminal 110 and satellite 102.

If a UT INE request at block 430 is received on the granted UL resourcefor the extracted short UT address in the following radio frames, atblock 432, SAT UMAC 328 initiates an UT INE request to SAT CM 324. Here,the SAT UMAC 328 can send an INE request with a UT identifier (UUID) toSAT CM 324. In some cases, the UT INE request to SAT CM 324 canoptionally include optional UT CM blobs. As a response to an UT INErequest, SAT CM 324 sends SAT UMAC 328 a response with a new assignedservice-identifier (SID) or other unique identifier and other L3 blobconfigurations, at blocks 436-444. SAT UMAC 328 sends user terminal 110an UT INE response addressed to R-SID and including the new grantedSID/identifier, at block 446.

The short UT address included in the INE request to SAT CM 324 is usedby SAT CM 324 to generate a UT authorization message, at block 434. TheUT authorization message comprises a request to network 124 toauthenticate and register the user terminal 110 to operate within thesystem 100. The UT authorization message is communicated to network 124via gateway 120, at blocks 436, 438.

In some embodiments, network 124 includes a label and address service(LAS) component configured to authorize entry of user terminals to thenetwork. LAS component of network 124 performs requisite processing onthe information provided in the UT authorization message to authorize(or not authorize) the user terminal 110. Requisite processing includesdetermination of certain information exchange occurrence between theuser terminal 110, satellite 102, and network 124, including certaininformation exchange between UT CM 304 and SAT CM 324 and between SAT CM324 and the LAS. If authorization checks are satisfied, LAS componentgenerates a UT authorization response message, at block 440. The UTauthorization response message is communicated back to SAT CM 324 viagateway 120, at blocks 442, 444.

If the UT is authorized (positive response is received at block 444),then the satellite 102 is configured to generate and transmit an UT INEresponse message to the user terminal 110, at block 446. The INEresponse is addressed to the R-SID specified by the user terminal 110 inthe RACH request. If UT UMAC 308 detects a UT INE response, at block448, UT UMAC 308 generates an INE response message to UT CM 304indicative of such success, at block 450.

If the UT is unauthorized by network 124 or a failure indication isspecified in block 444, then the UT INE response generated andtransmitted by satellite 102 to user terminal 110 can be addressed toR-SID, indicate a failure, and optionally actions for the user terminal110 to perform such as, but not limited to, return to satellitediscovery mode, wait for a defined time period before attempting INEagain, attempt INE again on a different channel, frequency, orsatellite, and/or the like. Such UT INE response or the failure todetect a UT INE response is reported to UT CM 304 so that remedialactions can be taken to complete initial entry into the network.

In some cases, with receipt of a successful INE response, UT CM 304 canoptionally generate and exchange blob information with SAT CM 324, atblock 452. In some cases, SAT CM 324 can optionally generate andexchange blob information with UT CM 304, at block 454. Componentswithin the same node can also optionally exchange blob information witheach other. For example, UT CM 304 exchanges L3 blob information with UTL2 or MAC 312, SAT CM 324 exchanges L3 blob information for userterminal of interest (e.g., user terminal 110) with SAT L2 or MAC 332.Examples of blob information exchanged include, but is not limited to,SID, other identifier or label information, and/or the like. Optionally,if blob information exchange is not completed within a prescribed timeperiod, initial entry into the network may be restarted. Blobinformation exchange incompletion can be due to a L2 control plane breakduring the blob exchange because satellite 102 goes out of service,network 124 fails to provide a grant to the user terminal 110, and/orlike. In some cases, if UT CM 304 fails to obtain the updated schedulefrom the LAS within a certain time after the effective time, as will bediscussed below, initial network entry process may be restarted.

Exchange of blob information can occur (when implemented) using the L2control plane established between the satellite 102 and user terminal110. Control plane is used to exchange control messages betweenentities.

SAT CM 324 can be configured to facilitate with SAT UMAC 328 to update acontext associated with user terminal 110 with the new SID/effectivetime information, at block 456, and to update the new SID in SAT L2/MAClayer 332, at block 458. The new SID/effective time information is usedin future UL-map generation. The new SID replaces the short UT addressused for INE purposes. In some cases, UT CM 304 can optionally beconfigured to facilitate with UT UMAC 308 to perform de-configuring theUT L2/MAC layer 312 (e.g., perform MAC down) and re-configuring the UTL2/MAC layer 312 (e.g., perform MAC up) with the new SID.

Next, satellite 102 continues to sequentially generate and transmitUL-maps, at block 460. Each UL-map can include specification of ULresources allocated to the user terminal 110 and such allocation can beassociated with the new SID (the unique identifier of user terminal 110for normal operations within system 100).

Blocks 462-464 can include one or more operations that are performedafter the effective time specified in block 456. Scheduling updates andcontrol plane schedule updates associated with downlink, uplink,operating frequencies, operational states of nodes, and/or the like aregenerated and/or exchanged between network 124, gateway 120, SAT CM 324,and UT CM 304, at block 462. Data exchanges can also take place betweenUT L3 306 and SAT L3 326, at block 464. In some examples, the schedulingupdates can include the new SID.

Accordingly, a RACH procedure is implemented to configure the L2/MACcontrol plane between the user terminal 110 and satellite 102. A L2-CMinterface is provided at each of the user terminal 110 and satellite 102in order to exchange control messages between UT CM 304 and SAT CM 324.Prior to completion of initial network entry, the L2 control plane canbe available between user terminal 110 and satellite 102. Prior tocompletion of initial network entry, no data packet exchange can occurbetween UT CM 304 and LAS included in network 124 on the data plane.

As discussed above, UT UMAC 308 of UT L2/MAC 312 and SAT UMAC 328 of SATL2/MAC 332 are configured to support random access in the uplink (e.g.,communicate a RACH request in the uplink). The random access compriseslogical RACH resources, not physical RACH resources. The UL-map providedby satellite 102 specifies where the RACH resources can be located in aUL radio frame transmitted by the user terminal 110 and other userterminals within the same cell. RACH resources for initial network entryare separate from other RACH resources such as for bandwidth request(BR).

FIG. 6 illustrates an example UL radio frame 600 including a pluralityof RACH resources in accordance with various aspects of the presentdisclosure. User terminal 110 generates UL radio frame 600 in accordancewith RACH resources for initial network entry specified by a UL-mapprovided by satellite 102 (e.g., UL-map provided at block 418). The RACHrequest at block 416 is included in UL radio frame 600.

In some embodiments, UL radio frame 600 comprises a plurality ofresource blocks (RBs) 604 composing a grid pattern in the frequency andtime domains. Each RB of the plurality of RBs represents a container fora unit of data (or message or request) to be transmitted in the uplink.Each column of RBs comprises an OFDM symbol 603. UL radio frame 600comprises a plurality of OFDM symbols 603 with the first OFDM symbol 602comprising a unique word (UW) which identifies the start of a burst ofthe radio frame.

At the end of UL radio frame 600 in the time domain is a dedicatedlocation for a plurality of RACH resources. Each RACH resource comprisesten contiguous RBs—five RBs in the frequency domain and two RBs in thetime domain. 239 data subcarriers, for example, can comprise a RACHresource. A burst synchronization symbol and a channel estimation (CE)symbol can be associated with each RACH resource, the CE symbolproviding information about the channel quality. Four RACH resources areincluded per OFDM symbol 603. A total of twelve RACH resources are shownin FIG. 6 , including RACH resources 608, 610, 612, 614, and 616. RACHresources 608, 610, 612, 614 are contiguous to each other in thefrequency domain. RACH resources 608 and 616 are contiguous to eachother in the time domain.

The number of RBs per RACH resource and the total number of RACHresources per radio frame discussed above are examples only and candiffer from those discussed above within the scope of the presentdisclosure.

In some embodiments, the data contained in a RACH resource (e.g., theRACH request) comprises a MAC protocol data unit (PDU) that is 64 bitsencoded using the most conservative modulation and coding scheme (MCS),for example, MCS 0. The MAC PDU is carried on the RACH channel specifiedby the UL-map. MAC PDU includes a MAC header, zero or more MAC servicedata units (SDUs) (the payload data), and one or more other fields. TheMAC header can include a signaling MAC header, one or more signaling MACextended headers, and a MAC header cyclic redundancy check (CRC).

UT UMAC 308 generates the MAC PDU encoding the RACH request. UT UMAC 308selects a RACH resource from among the plurality of RACH resourcesincluded in UL radio frame 600 into which to include the MAC PDUcomprising the RACH request. Because the user terminals performinginitial network entry each independently select a particular RACHresource from among the plurality of RACH resources allocated by theUL-map (as opposed to the satellites making the selection), if more thanone user terminal includes a RACH request in the same RACH resource inits uplink radio frames configured to arrive at satellite 102 at thesame time, there can be collision of signals such that all of theindividual RACH requests may not be able to be extracted. Accordingly,the receiver (Rx) PHY-MAC interface at the satellite 102 is configuredto analyze the power strengths of various portions of the received radioframes from the user terminals to detect potential signal collusionsbetween RACH requests in order to only pass quality or “good” RACHrequests to SAT UMAC 328 of SAT MAC 332.

FIG. 7 illustrates an example process 700 for detection of RACH requestsin accordance with various aspects of the present disclosure. In someembodiments, UL-MAP configuration to remote monitoring modem (RMM)translation occurs in the satellite's 102 receive (Rx) modem. The Rx PHYmodem hardware can determine whether received RACH request(s) in each ULradio frame can be sufficiently separated from other RACH requests inthe same UL radio frame and is of sufficient signal quality to pass ontothe SAT LMAC 330 of SAT MAC 332, when RMM is configured with RACH slots.

A set of RACH slot counters per receive UL radio frame and per each RACHtype (INE, BR) is maintained. The set of RACH slot counters comprises asingle counter, an empty counter, a collision type 1 counter, acollision type 2 counter, and a collision type 3 counter. At the startof the next radio frame, the counters are reset to zero. RMM is aware ofthe RACH resources location within each radio frame and the type of RACHresources (INE, BR). If the MAC PDU comprising the RACH request ispassed to SAT MAC 332, then SAT L1 334 is also configured to communicatesideband signal information to SAT MAC 332. Sideband signal informationcomprises whether the PDU was carried in a shared resource or ascheduled resource, if the PDU was carried in a RACH resource, andwhether the RACH resource is an INE RACH resource or a BR RACH resource.

At a block 702, RMM (with the PHY hardware performing the calculation)is configured to calculate the denoised power from CE symbols associatedwith the received MAC PDUs. The denoised power from a burst detection(using burst synchronization symbol) in the time domain is expressed asfollows.

$\begin{matrix}{P_{denoised\_ uw} = {{{abs}\left( {{h_{{matched}_{out}}\left( {{peak} + 256} \right)}*{h_{{matched}_{out}}^{*}({peak})}} \right)} \approx {h^{2} + \frac{\sigma^{2}}{128}}}} & {{Eq}.(1)}\end{matrix}$where

${h_{matched\_ out}(n)} = {\frac{{conv}\left( {{x_{{sync}_{in}}(n)},{uw}_{seq}} \right)}{128} = {h + {\overset{\sim}{n}{with}{x_{{sync}_{in}}(n)}}}}$is the time—domain received signal, uw_(seq) is the burstsynchronization sequence in the time—domain,

${{{var}\left( \overset{\sim}{n} \right)} = \frac{\sigma^{2}}{128}},$and σ² is the power of AWGN noise.

The denoised power from CE symbols in allocated in RBs of the MAC PDUsin the frequency domain is as follows.

$\begin{matrix}{P_{denoised\_ CE} = {{{abs}\left( \frac{\sum{{h_{ce}(n)}*{h_{ce}^{*}\left( {n - 1} \right)}}}{N_{sc}} \right)} \approx h^{2}}} & {{Eq}.(2)}\end{matrix}$where N_(SC) is the number of allocation subcarriers in frequency domainof the CE symbol and h_(ce) is the raw received signal per subcarrier ofthe CE symbol. It is assumed that the noise term among subcarriers isindependent of each other.

If the denoised power from CE at block 702 is less than a pre-setthreshold (yes branch of block 704), then process 700 proceeds to block706. At block 706, an error check (e.g., CRC) is performed using the MACheader CRC field information. If the error check fails (yes branch ofblock 706), then process 700 proceeds to block 708. The PHY hardware hasdetermined that the received RACH requests collide, superimpose, orotherwise commingle with each other in one or both of the frequency ortime domains so as to cancel each other. Thus, none of the RACH requestscan be resolved or separated from each other; and no RACH requests canbe passed to SAT LMAC 330. Accordingly, the empty counter isincremented, at block 708. The empty counter maintains a count of errorcases.

If the error check passes (no branch of block 706), then process 700proceeds to block 710. At block 710, the collision type 2 counter isincremented. Although the RACH request signals from different userterminals collided (e.g., superimposed, commingled, combined in one orboth of frequency or time domains), one of the signals is sufficientlydetectable or resolvable. The sufficiently detectable signal is passedto SAT LMAC 330 to continue initial network entry for that userterminal.

If the denoised power from CE is equal or above the threshold (no branchof block 704), then process 700 proceeds to block 712. Block 712performs an error check similar to block 706. If the error check fails(yes branch of block 712), then process 700 proceeds to block 714. Atblock 714, the collision type 1 counter is incremented. Although theRACH request signals from different user terminals collided (e.g.,superimposed, commingled, combined in one or both of frequency or timedomains), both signals can be sufficiently separately detected orresolved. Each of the separately detectable signals is passed to SATLMAC 330 to continue initial network entry for respective userterminals.

If the error check passes (no branch of block 712), then process 700proceeds to block 716. If the denoised power from CE is greater than ahigh threshold (a threshold value higher than the threshold for block704) (yes branch of block 716), then process 700 proceeds to block 720.At block 720, the collision type 3 counter is incremented. Collisiontype 3 counter is associated with the RACH Request signals colliding andbeing additive together. Accordingly, the individual signals cannot beseparated and no signals are passed to SAT LMAC 330. The user terminalsassociated with these signals will restart initial network entry.

If the denoised power from CE is less than the high threshold (no branchof block 716), then process 700 proceeds to block 718. At block 718, thesingle counter is incremented. Single counter is associated withsatellite 102 receiving a single INE RACH request in that radio frame.The single RACH request is passed to SAT LMAC 330.

FIG. 8 illustrates a block diagram showing an example platform or devicethat can be implemented in the user terminal 110 and/or satellite 102 inaccordance with various aspects of the present disclosure. Platform 800comprises at least a portion of any of components 302-316 and 324-336.Platform 800 as illustrated includes bus or other internal communicationmeans 815 for communicating information, and processor 810 coupled tobus 815 for processing information. The platform further comprisesrandom access memory (RAM) or other volatile storage device 850(alternatively referred to herein as main memory), coupled to bus 815for storing information and instructions to be executed by processor810. Main memory 850 also may be used for storing temporary variables orother intermediate information during execution of instructions byprocessor 810. Platform 800 also comprises read only memory (ROM),static storage, or non-volatile storage device 820 coupled to bus 815for storing static information and instructions for processor 810, anddata storage device 825 such as a magnetic disk, optical disk and itscorresponding disk drive, or a portable storage device (e.g., auniversal serial bus (USB) flash drive, a Secure Digital (SD) card).Data storage device 825 is coupled to bus 815 for storing informationand instructions.

The processes explained above are described in terms of computersoftware and hardware. The techniques described may constitutemachine-executable instructions embodied within a tangible ornon-transitory machine (e.g., computer) readable storage medium, thatwhen executed by a machine will cause the machine to perform theoperations described. Additionally, the processes may be embodied withinhardware, such as an application specific integrated circuit (ASIC) orotherwise.

A tangible machine-readable storage medium includes any mechanism thatprovides (e.g., stores) information in a non-transitory form accessibleby a machine (e.g., a computer, network device, personal digitalassistant, manufacturing tool, any device with a set of one or moreprocessors, etc.). For example, a machine-readable storage mediumincludes recordable/non-recordable media (e.g., read only memory (ROM),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, etc.).

Although certain embodiments have been illustrated and described hereinfor purposes of description, a wide variety of alternate and/orequivalent embodiments or implementations calculated to achieve the samepurposes may be substituted for the embodiments shown and describedwithout departing from the scope of the present disclosure. Thisapplication is intended to cover any adaptations or variations of theembodiments discussed herein. Therefore, it is manifestly intended thatembodiments described herein be limited only by the claims.

What is claimed is:
 1. A user terminal comprising: one or moreprocessors coupled to a memory, the one or more processors beingconfigured to generate an initial network entry request; an antennaassembly configured to find, in response to the initial network entryrequest, a satellite based on a search of a sky, wherein the search ofthe sky comprises sequentially changing a beam pointing direction of theantenna assembly, wherein the satellite is assigned to downlink to ageographic cell associated with the user terminal; and a media accesscontrol (MAC) layer component configured to generate an uplink radioframe including a random access channel (RACH) request associated withthe initial network entry request at a particular portion of the uplinkradio frame for the satellite, wherein the particular portion isselected by the MAC layer component from among a plurality of portionsof the uplink radio frame.
 2. The user terminal of claim 1, wherein theplurality of portions of the uplink radio frame comprises a plurality ofRACH resources allocated by an uplink (UL)-map received from thesatellite, and wherein the plurality of RACH resources are located at anend of the uplink radio frame in a time domain.
 3. The user terminal ofclaim 2, wherein each RACH resource of the plurality of RACH resourcescomprises contiguous resource blocks within the uplink radio frame. 4.The user terminal of claim 2, wherein the uplink radio frame comprises aplurality of orthogonal frequency division multiplexing (OFDM) symbols,and wherein more than one RACH resources of the plurality of RACHresources is included in an OFDM symbol of the plurality of OFDMsymbols.
 5. The user terminal of claim 1, wherein the RACH requestincludes a temporary service identifier of the user terminal selected bythe MAC layer component.
 6. The user terminal of claim 5, wherein theRACH request includes an identification blob associated with thetemporary service identifier to be used for contention resolution. 7.The user terminal of claim 5, wherein the one or more processors areconfigured to receive a new service identifier of the user terminal fromthe satellite after authorization into a network, and wherein the newservice identifier replaces the temporary service identifier and the newservice identifier comprises a unique identifier of the user terminalwithin the network.
 8. The user terminal of claim 1, wherein the RACHrequest is included in a MAC protocol data unit (PDU) and the MAC PDU isencoded using modulation and coding scheme (MCS)
 0. 9. The user terminalof claim 1, wherein the antenna assembly is configured in a receive modeto find the satellite.
 10. The user terminal of claim 1, wherein the oneor more processors are configured to generate the initial network entryrequest via a connection manager component, wherein the user terminaluses a same temporary service identifier for the initial network entryrequest as a second user terminal that initiates another network entryrequest at approximately a same time as the initial network entryrequest, wherein the user terminal selects a temporary serviceidentifier independent of other user terminals and the satellite, andwherein the user terminal resends a request to initiate network entry.11. A system comprising: first and second user terminals configured tofind a satellite based on a search of a sky, wherein the search of thesky comprises sequentially changing a beam pointing direction ofrespective antenna assemblies of the first and second user terminals toinitiate network entry to a communications system, wherein the firstuser terminal is configured to generate and transmit a first radio frameto be received by the satellite at a first time period, the first radioframe including a first initial network entry request at a first portionof the first radio frame, the first portion selected by the first userterminal, and wherein the second user terminal is configured to generateand transmit a second radio frame to be received by the satellite at thefirst time period, the second radio frame including a second initialnetwork entry request at a second portion of the first radio frame, thesecond portion selected by the second user terminal independent of thefirst user terminal.
 12. The system of claim 11, wherein the satelliteis configured to combine the first and second radio frames to generate asingle received radio frame, and wherein the first and second portionscomprise different portions of the single received radio frame.
 13. Thesystem of claim 11, wherein the satellite is configured to combine thefirst and second radio frames to generate a single received radio frame,and wherein the first and second portions comprise a same portion of thesingle received radio frame.
 14. The system of claim 13, wherein thefirst and second initial network entry requests cancel out each other,and the first and second user terminals restart initiation of networkentry.
 15. The system of claim 13, wherein the first and second initialnetwork entry requests commingle with each other in one or both of afrequency domain or a time domain, and the first initial network entryrequest is extractable for the satellite to respond to the first initialnetwork entry request.
 16. The system of claim 13, wherein the first andsecond initial network entry requests commingle with each other in oneor both of a frequency domain or a time domain, and the first and secondinitial network entry requests are separated from each other for thesatellite to respond to each of the first and second initial networkentry requests.
 17. The system of claim 13, wherein the first and secondinitial network entry requests are additive of each other in one or bothof a frequency domain or a time domain, and the first and second userterminals restart initiation of network entry.
 18. The system of claim11, wherein the first initial network entry request comprises a randomaccess channel (RACH) request included in an uplink channel allocatedfor RACH procedures and a RACH resource location in the first radioframe.
 19. The system of claim 18, wherein the RACH resource location isspecified by an uplink (UL)-map provided by the satellite prior togeneration of the first radio frame.
 20. A method comprising: generatingan initial network entry request; in response to the initial networkentry request, finding, via an antenna assembly of a user terminal, asatellite based on a search of a sky, wherein the search of the skycomprises sequentially changing a beam pointing direction of the antennaassembly, wherein the satellite is assigned to downlink to a geographiccell associated with the user terminal; and generate, via a media accesscontrol (MAC) layer component, an uplink radio frame including a randomaccess channel (RACH) request associated with the initial network entryrequest at a particular portion of the uplink radio frame for thesatellite, wherein the particular portion is selected by the MAC layercomponent from among a plurality of portions of the uplink radio frame.